Production of spindle blades



Patented Aug. 22, 1939 UNlTEDgS TATES PATENT OFFICE V 7 I I 2,1 70,7 2i

v PRODUCTION OF SPISNDLEIELADES Harry Mitchell, Whitinsville, Mass., assignor to Whitin Machine Works, Whitinsville, Mass, a corporation of Massachusetts 7 Ya No Drawing. Application July 17, 1937, 1 I Serial-No. 154,205

1 Claim. (01. 29 -517 F This invention relates to the spindle blades used in spinning and twisting machines. The general object of the invention is to provide a spindle blade of'improved wearing qualities and of more uniform hardness, and also to produce such a blade by a much simplified process.

The blade of a spinning or twisting spindle is an elongated bar of steel, commonly provided with a middle portion on which a driving pulley or spindle whirl is seated, a lower tapered bearing portion rotatable in a spindle bolster, a sharply pointed lower end or step bearing portion supported on an associated thrust member or spindle step, and a tapered and relatively slender upper portion on which a cop or bobbin is mounted for rotation therewith.

It is customary, to manufacture such spindle blades from bars of carbon steel which may be easily machined before hardening. These bars are first rough-turned to approximate dimen-- sions, are then highly hardened, commonly to about 64 on the Rockwell 0 scale, are then drawn or tempered to about 58 on said scale and are thereafter ground all over, The lower end or step bearing portion of the blade is then rehardened to approximately 64 Rockwell C, after which this end portion is ground to a sharply tapered point and the remainder of the blade is highly polished.

An intermediate inspection for straightness is made between tempering and grinding, and nearly all of the blades require straightening which is a slow and tedious operation and is also an operation requiring great skill. Frequently also a further straightening is required after the second hardening of the lower end or step bearing portion.

, When a spindle blade produced as above described is submitted to hardness tests, it is found that the spindle has a very hard step bearing portion, a relatively soft and easily bendable portion directly above the step bearing, and an upper portion of intermediate hardness.

Such a spindle is subject to unusual wear at 45 three points; namely, at the lower end or step bearing portion, at the tapered bolster bearing portion, and at the upper end of the spindle blade. The greatest wear takes place at the upper end of the blade and is caused by the chatter and vibration of unbalanced bobbins. Without actual proof, the amount of wear which will take place between an unbalanced wooden bobbin and a hardened steel spindle with which it rotates would not be believed.

According to my present invention, I provide a spindle blade of such composition and method of production that no special hardening or tempering operations are needed, that little straightening is required, and that substantially uniform hardness throughout the length of the spindle 5 blade is provided and retained.

To accomplish this result, I form my improved spindle blades from bars of special air-hardening steel alloy. The normal air-hardness of these steel bars is from 60 to 62 Rockwell C, and the 10 blades are formed from these bars entirely by a grinding operation, as the normal steel is too hard to permit effective use of turning tools.

After the blades are ground to shape, no further treatment thereof nor operations thereon are 15 required, and the spindles are ready to receive the whirls and to be shipped immediately thereafter. Only in exceptional cases is any straightening whatever required.

I have found that my improved spindle blades 20 may be made to best advantage from a steel alloy of relatively low carbon content but containing substantial amounts of chromium, nickel and molybdenum. Such a steel alloy has the property of acquiring uniform high hardness 25 when cooled in air, and the air-cooling and airhardening may be performed at a relatively slow rate, thus avoiding surface cracks,

Steel bars thus manufactured are found to possess substantially uniform high hardness for their 30 full length and throughout the lot, and they are of such grain and texture that they are highly Wear-resistant. The steel is also in such a condition that it possesses plastic deformation properties, due to which the hardness of the steel will be actually increased by use.

It has been found by experiment that the step bearing portion of a spindle blade produced as described from a chromium-nickel-molybdenumv steel alloy will have a hardness of 60 to 62 Rockwell C when first made, but will increase to a hardness of 63 to 64 by continued use.

It has also been found by experimental tests that the step bearing and tapered bolster bearing portions of my improved spindle blade show no appreciable wear after prolonged operation, and furthermore that the upper end portion of the spindle effectively resists the wear caused by the chatter or vibration of unbalanced bobbins.

A comparative test carried out by running spindles with both old and new type blades side by side under load for equal periods of time discloses no appreciable wear on the new type blades but very substantial flattening of the sides of the upper end portions of the 01d type blades, i

which flattening is often 10% or more of the diameter of the upper part of the blade.

While the advantages of my improved production of spindle blades may be attained to a certain extent by the use of a considerable range of air-hardening steels, I have found the following composition, subject to slight variations, to be highly satisfactory:

Carbon .50 Manganese .55' Chromium .90 A Nickel 1.50 ,Molybdenum .50 Iron 96.05

While such a steel alloy is naturally more expensive than the carbon steel commonly used, the production of my improved spindle blade is correspondingly simpler and less expensive, and

20 furthermore the loss by breakage or injury of uniform initial hardness, said spindle blade being formed from said bar entirely by grinding operations, with the initial hardness of the steel substantially maintained during the production of said blade, and said steel bar and spindle blade comprising approximately .50% carbon, .50% manganese, 1% chromium, 1.50% nickel and .50% molybdenum, said steel bar being initially air-hardened to approximately 60 on the Rockwell C scale.

HARRY MITCHELL. 

